The invention relates to means for the visual display and storage of data recorded on a magnetic medium, such as a magnetic card or tape. It more specifically relates to a device of the "magnifying glass" type placed on the recorded medium and which reveals the magnetic information by the displacement of a pulverulent solid.
Magnetic recording is an extremely convenient way to process or store data and is at present widely used. It is possible to manipulate or convert into magnetic signals all types of information, no matter whether they are analog, e.g. television pictures, music, manufacturing variables in an industrial process or digital, e.g. particularly in information processing. The interest in converting data into magnetic signals is increased by the varied and economic advantages of recording media, whose scope ranges from the magnetic computer memory or the tape storage of television pictures to a simple identification track on a card, badge or ticket. However, all these media or supports, or more specifically the magnetic recording, suffer from one important disadvantage compared with other storage means and that is that the content is not visible to the human eye. To identify the content of a recording or read the message or join two recorded elements, it is necessary to use relatively complex means when compared with the simplicity of the recording. Examples of such means are the tape recorder for music, the visual tape recorder for pictures or the display unit for digital signals, without this list being in any way complete.